See i this helps

Sub FillColBlanks()
'by Dave Peterson  2004-01-06
'fill blank cells in column with value above
Dim wks As Worksheet
Dim rng As Range
Dim LastRow As Long
Dim col As Long

Set wks = ActiveSheet
With wks
   col = ActiveCell.Column
   'or
   'col = .range("b1").column

   Set rng = Cells(1600, ActiveCell.Column) 'try to reset the lastcell
   LastRow = 1600
   Set rng = Nothing
   On Error Resume Next
   Set rng = .Range(.Cells(2, col), .Cells(LastRow, col)) _
                  .Cells.SpecialCells(xlCellTypeBlanks)
   On Error GoTo 0

   If rng Is Nothing Then
       MsgBox "No blanks found"
       Exit Sub
   Else
       rng.FormulaR1C1 = "=R[-1]C"
   End If

   'replace formulas with values
   With .Cells(1, col).EntireColumn
       .Value = .Value
   End With

End With

End Sub
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